Effect of Drying Conditions on Rheological Properties of Hydrocolloids Gums from <i>Triumfetta cordifolia</i> and <i>Bridelia thermifolia</i> Barks
- 1 Départment of Food Sciences & Nutrition, University of Ngaoundéré, Ngaoundéré, Cameroon;Laboratory of Rheology, University of Joseph Fourier, Grenoble University, Grenoble, France
- 2 Laboratory of Rheology, University of Joseph Fourier, Grenoble University, Grenoble, France
- 3 Laboratory of Rheology, University of Joseph Fourier, Grenoble University, Grenoble, France
- 4 Départment of Applied, University of Ngaoundéré, Ngaoundéré, Camer- oon
- 5 Laboratory of Function and Structure of Polysaccharids, Center of Vegetables Macromolecules Research, Grenoble, France
- 6 Laboratory of Rheology, University of Joseph Fourier, Grenoble University, Grenoble, France
Abstract
Triumfetta cordifolia and Bridelia thermifolia are two shrubs from tropical region of Africa. Their gums are traditionally extracted from fresh barks and used in traditional recipes (thickening and aromatization of sauces, improvement of the swelling of maize and bean cakes) and in the process of decantation of traditional beer. In order to valorize these barks in dried form, study of the effect of drying temperature on the rheological properties of their gums was carried out. In this respect, the fresh barks were dried at 40℃, 50℃, 60℃, 70℃ and 80℃ and the viscosity of their extracts was measured. The drying kinetic of the barks showed two falling rate periods represented by two drying constants k 1 and k 2 . The absolute viscosity of the extracts decreased beyond drying temperatures higher than 70℃ and 80℃respectively for T cordifolia and B. Thermifolia . The decreasing viscosity is attributed mainly to a reorganization of polysaccharide chains. The temperatures range lower than 70℃ could be retained to dry the barks and to extract gums without deteriorating their properties.
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